Dental stool.



C. M. HEDMAN.

DENTAL STOOL.

APPLICATION FILED JULY 17, 1912.

Patented Dec. 21, 1915.

COLUMBIA PLANOURAPH CDHWASHINOTON D. c.

ably be placed under initial tension.

piarria sraaras partner on UATtL M. HEDMAN, OF CHICAGO, ILLIITGTS, ASSIGNUR Ti) LEE S. SMITH AND W. LIND- IEORD SMITH, COPARTNERS DQING BUSINESS AS LEE S. SMITH & SON COMPANY, (1F

PITTSBURGH, PENNSYLVANIA.

DENTAL STOOL.

Original application filed July 31, 1911, Serial No. 641,617.

Divided and this application filed July 17, 1912.

To all whom it may concern:

Be it known that I, CARL M. HEDMAN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and use ful Improvements in Dental Stools, of which the following is a full, clear, concise, and

exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to vertically adjustable dental stools or the like, and has for its object the provision in an article of this class of a simple and highly efhcient method of raising the seat rod or post in the supporting standard, to efiectually lock the same in any desired position of vertical adjustment; also to provide means whereby the supporting standard may be moved slightly back and forth while the operator is at work, without moving the base.

The present application is divisional of application Serial No. 641,617, which has matured into a patent granted to me under date of November 19th, 1912, No. 1,04A,523.

The operation, construction and arrangement of the parts of my invention are fully described in the following specification, and. illustrated in the accompanying drawings, in which- Figure 1 is a side elevation of my improved stool shown partly in cross-section, and Fig. 2 is a detail view of the clutch mechanism for retaining the seat post at the desired height in the standard.

Referring to the drawings, 1 designates a stool base of any suitable material carrying a hollow head 2. "Within this hollow head is an inwardly extending shoulder 3 located a small distance beneath the upper end of the head. Fitting tightly within the hollow head 2 and resting on the shoulder 3 is a helical spring 41. This spring, which is forced into the hollow head, should prefer- L h ring 5 rests on the shoulder 3 inside of and fitting tightly against the helical spring. This ring is driven into this position and there spread, forcing the helical spring tightly against the wall of the hollow head 2 which Patented Dec. 21, 1915.

Patented November 19, 1912, No. 1,044,523.

Serial No. 709,924.

may be provided with internal threads to hold the spring 4- more rigidly. T have found in practice, however, that the method shown in the drawings is very eliicient and that these threads are not absolutely necessary.

A hollow standard 6, provided with'a base 7 secured thereto, is supported by the top of the spring 1. A conical plug 8 is secured in theend of the standard 6 and projects down through the spring and inside of the ring 5. This plug forms a closure for the bottom of the hollow standard 6 and at the same time serves as a support for the standard when the spring is bent far enough from the vertical to bring the end of the plug against the ring 5 and the shoulder '3. A; seat post 9 telescopes with the hollow standard 6 to provide for different heights at which theoperator may desire the seat to be placed. A spring 11 tends to raise the seat post 9 to its uppermost position, but means, later to be described, is provided for holding it at any position.

One side of the post 9 is notched as by milling to produce the projections 10. A yoke 12 surrounds the top of the hollow standard 6 and is secured thereto. The yoke 12 supports a pivoted lever 13 by means of a pin 24. The lever 13 is provided with a cam 1 1 in the shape of a hardened steel pin projecting from the face of the lever which face is presented toward the teeth 10. This pin 14: is provided with a beveled surface on the bottom side thereof as indicated in the drawings, and a spring 15 is provided in the sockets 16 and 17 for holding the pin 1d against one of the teeth 10. The pin 14 is mounted on the short arm of the lever between the post and on the pivot 2 1 so that the downward movement of the handle on the lever 13 will swing the pin 14: in a clockwise direction as seen in Fig. 2 and will disengage the pin from the projections 10. This allows the spring 11 to raise the seat post 9.

In order to prevent the seat post 9 from turning, a pin 18 which may be screwed into the yoke 12 and the standard 6 in order to or key-way 19 cut into the opposite side of the seat post 9. This insures a correct alinement of the projections 10 with the cam member 1a. A suitable seat 23 may be secured on the top of standard 6 preferably by an anti-friction bearing such as a ball bearing 21. The seat and the post are secured together by means of the pin 22 and the groove 20 on the end of the post.

The operation of the device is as follows: When it is desired to release the post 9 in order to set it at the desired height, pressure is applied on the end of lever 13. This swings the pin 14 out of engagement with the projections 10 and allows the spring 11 to raise the seat. The seat may be lowered by applying pressure to overcome the tension of spring 11. lVhen it is desired to lock the seat at the given height, the lever 13 is released. The spring 15 casts the pin 14 into the projections 10 and the pin is thereby caught. If the weight of the op-' erator is now placed upon the seat, the pin 14L will be rotated about the pivot 24: in a counterclockwise direction because one of the projections 10 is applying downward pressure. Such rotation of the lever 13 about its pivot 2st forces the pin 14 against the post 9 between two adjacent projections 10; This binds the post between the hollow standard 6 included within the yoke 12 and the pin 14. The greater the pressure applied on the seat 23, the greater will bethe tendency for the post 9 to bind due to the cam action described.

This structure is not to be confused with the ordinary pawl and ratchet mechanism which has heretofore been employed.

All of the parts of this dental stool are of very simple but durable construction. The seat may be raised or lowered by the operator and the operator may move back and forth while seated thereon by reason of the flexible spring 4.

I claim as new and desire to secure by Letters Patent, the following:

1. In a dental stool,a hollow standard having a yoke embracing the top of said standard, a seat post longitudinally movable in said standard, said post having a longitudinal groove therein, a pin passing through said yoke and standard and projectinginto said groove, a spring tending to lift said post, lateral projections on said post, a lever pivotally mounted on said yoke, a pin mounted on the edge of said lever and projecting into the path of said projections, a spring tending to hold said lever to present said pin to said projections, said lever being of such length as to cause the pin to become wedged between the post and the pivot on the yoke to clamp the post against the inside surface of the yoke.

2. In combination a hollow standard, a

yoke secured to said standard, a. l ver pivotally mounted intermediate its ends on said yoke and having its one end projecting into the hollow space in said standard, a post longitudinally slidable in said standard and being engaged by said end of said lever, said end of the lever being of such length as to bind frictionally between its pivot and the post, a springin said standard, said spring pressing said post in a direction to prevent binding of said post with said end of the lever, and lateral projections on said post for engaging said end of the lever, when the post is moved in the opposite direction to cause the said end of the lever to bind the post in said yoke against movement in either direction, the other arm of the lever having a handle for releasing the post.

3. In combination 'a stool comprising a hollow standard, a seat post movable longitudinally in said standard, a yoke embracing said standard, a spring tending to lift said post, a plurality of recesses on said post, a lever mounted on said yoke, a pin having a reduced end mounted on the end of said lever, said lever and pin being of such a length as to wedge the pin in one of said recesses between the post and the pivot of the lever, thereby holding the post against motion in either direction, and a spring tending to force said pin into engagement with the recesses in said post, downward pressure upon said post causing said pin to be forced into engagement with said post to wedge between the post and the pivot on the yoke, to grip the same securely, said lever having a longer arm bearing a handle for releasing the pin from engagement with said post.

4. In combination a hollow tubular standard, a U-shaped yoke embracing the top of said standard, a lever having a pivot pin mounted in the arms of said U-shaped yoke, said lever comprising a short arm and a longer arm, a round seat post slidable in said standard, said post having a row of transverse notches on one side thereof, and having a spline out along part of the length thereof, a pin projecting into said spline, the shorter arm of said lever bearing a hardened steel pin for engagement with the notches cut into said post and a spring tending to cast said shorter arm of the lever into said notches and a spring tending to lift said post, the arm bearing the pin being wedged between the pivot pin and the post upon downward movement of said post, said longer lever arm having a handle portion for releasing the shorter arm.

5. In combination a yoke having a lever pivoted thereupon, a post projecting through said yoke and having a series of projections thereupon, said lever having a short arm lying between the post and the pivot point on the yoke, and a long arm provided with a against the post, and a spring for said post handle, lying on the outside of the pivot tending to raise the same. 10 point, said short arm being provided with In Witness whereof, I hereunto subscribe means to engage one of the projections on my name this 2nd day of July, A. D. 1912.

- the post and to wedge between the pivot CARL M. HEDMAN.

and the post in order to bind the post in the Witnesses: yoke against movement, a spring for said HARVEY L. HANsoN, lever tending to throw said shorter arm ALBERT G. MCOALEB.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. i 

